The preliminary options and arguments returned from
`.parse_preliminary_options_and_args()` are now all threaded through to
the appropriate methods during initialization.
The configuration file and boolean to ignore configuration files can be
threaded through now that `.parse_preliminary_options_and_args()`
returns options and arguments.
Now that `.parse_preliminary_options_and_args()` returns options and
arguments, the boolean for appending configuration and the arguments can
be threaded through to the creation of the `ConfigFileFinder`.
The verbosity and output file options can be obtained from options
returned by `.parse_preliminary_options_and_args()`, instead of state
from the `Application` object.
This is the initial step towards removing state from the `Application`
object during argument parsing and handling. The goal is to remove
`Application.prelim_opts` and `Application.prelim_args`.
When calling `ArgumentParser.parse_args()` with the `namespace`
argument, command-line options are just added to the namespace without
going through any of the argument parsing and type conversion logic
(e.g., the `type` keyword argument of `ArgumentParser.add_argument()`).
In other words, it is assumed that a namespace is well-formed from a
previous invocation of `ArgumentParser.parse_args()`.
The `values` parameter is intended to be values already-provided from
configuration files. To take advantage of the logic defined by
`ArgumentParser.add_argument()`, utilize
`ArgumentParser.set_defaults()` instead.
`flake8.main.cli.main()` is the primary entry point for the command-line
implementation of flake8 (invoked via `__main__` or `console_scripts`).
Therefore, it is reasonable for the entry point to be responsible for
obtaining command line arguments from `sys.argv` there.
Note that `sys.argv[1:]` is necessary in order to strip off the script
name. Formerly, this was not needed in
`Application.parse_preliminary_options_and_args()`, which was using
`sys.argv[:]` because the result of the argument parsing was just for
determining additional configuration to be loaded. Then, the *real* CLI
argument parsing was forwarding the original `None` value to
`argparse.ArgumentParser.parse_args()`, which internally was obtaining
arguments as `sys.argv[1:]`.
Additionally, the contract for various argument parsing methods to be
guaranteed a `List[str]`.
`flake8.main.cli.main()` is the primary entry point for the command-line
implementation of flake8 (invoked via `__main__` or `console_scripts`).
Therefore, it is reasonable for the entry point to be responsible for
obtaining command line arguments from `sys.argv` there.
Additionally, the contract for various argument parsing methods to be
guaranteed a `List[str]`.
Now that callers are ensuring that `value` is not `None`, we can further
tighten the contract and remove the conditional to account when `None`
is passed-in for `value`.
Additionally, add a new test vector to account for when an empty string
is passed in, which would fail `if no value`.
Now that the contract has narrowed for `utils.normalize_paths()`
and `utils.parse_comma_separated_list()`, `Option.normalize()` must
handle when the option value is either a singular value or a sequence
(i.e., `list`) of values.
The paths where `Option.normalize()` is called are:
1. options/config.py: `MergedConfigParser.parse_*_config()`
There are 3 paths wehre eventually `_normalize_value()` is called.
2. options/manager.py: `OptionManager.parse_args()`
For (1), values are coming from the `configparser` module. For (2),
values are coming from `optparse.OptionParser`.
Rudimentary investigation seems to implicate that
`optparse.OptionParser.parse_args()` always returns values in a `list`
because it accumulates values. However, for `configparser`, the values
are a string due to the key-value nature of the INI format.
Given that `Option.normalize()` is the convergence point where
normalization of an option occurs, it is acceptable for the method to
also handle the parsing comma-separated values and path normalization by
the option value's type.
